Electrical System tools

Boat Electrical System

Electrical System Tools


Few problems on board a boat are more vexing than electrical difficulties.

Engines that fail to start, electronics that we depend on for navigation that do not function properly or lights that wonít work when we need them can be mere inconveniences. But they can also endanger the safety of the boat and its crew if they affect critical circuits at inopportune moments.

The good news is that electrical system faults are among the easiest of all onboard problems to solve, but only if the proper tools are on hand to diagnose the fault and make a repair. Without the proper tools and parts, making electrical repairs can be impossible.

Here's a selection of electrical system tools that should be onboard every boat:

- A hydrometer tests the specific gravity of wet-cell batteries to assess their state of charge. If your boat has AGM or gell-cell batteries, you can omit the hydrometer and the water to fill the cells.


- Distilled water must be readily available to top up wet cells. Donít forget a funnel, turkey baster or other method of putting the water into the battery.

- A multimeter is the main testing tool for electrical circuits. If buying a new one, spend a few extra dollars to get one with a digital readout. A good mutimeter has the capability of reading voltage, ohms of resistance for use in tracing continuity and amps in small circuits. It should be able to read a minimum of 240 volts for working on shorepower or generator circuits.

- A polarity tester for 120-volt circuits protects your boat from damage at a marina with improper shorepower connections. If your boat doesnít have a polarity tester built into the electrical panel, a portable one is highly recommended. For rewiring projects on 120-volt circuits, a portable polarity tester is a necessity.

-Wire should be carried in sizes from 18 gauge to the largest battery cable on board. Should a wire or cable fail out on the water, you will have some way to bypass the bad section. Marine-grade tinned stranded-copper wire can be bought in most marine stores on small rolls that are ideal for this purpose.

Ancor Marine TM (www.ancorproducts.com) Grade wire electric products are the longest lasting and most rugged available on the market.

The Tinned Copper Wire, (0.8mm≤)- 18 AWG (0.8mm≤)

-Wire terminals are widely available in boxes of assorted sizes and types. Make sure your kit includes a good supply of butt and ring connectors in the three common sizes (yellow is for 10 and 12 gauge wire, blue for 14 and 16 gauge and red for 18 and 20 gauge). The ring terminals should have a good selection of stud sizes as well as wire gauge. Cable ends for size 8 wire and up to the size of the battery cables should also be on hand.

- Wire cutters capable of parting the largest wire with a good clean end must be in the tool box.


- Wire strippers with specific stripping sizes up to 10-gauge wire can remove wire covers quickly and cleanly without damaging the wire. For larger cables, a box-cutting knife with a retractable blade can be used if care is taken not to cut too deeply. Below you can see the Automatic Wire Stripper by Ancor.

- Wire crimps for installing terminals onto the wire ends are a necessity. For wire sizes of 8 gauge up to size 00 (double aught), a hand-sized Nicopress tool (nicopress.com) - also operated with a wrench works well.


- Combination cutter/stripper/crimper tools that perform all three of the functions above on up to 10-gauge wire are widely available, but many of them are inexpensive and poorly made, be sure that your tool will last for years and perform properly when it is needed.

- Spare parts carried on board should include light bulbs, fuses, switches and circuit breakers for common circuits. Concentrate on the circuits you rely on the most such as the bulbs for the running lights, the fuse for the GPS circuit and the circuit breaker size for the VHF radio. The loss of many other circuits will be a mere inconvenience until you can return to the dock and make repairs. Many circuits use the same size fuse or circuit breaker and you should carry multiple replacements of those sizes.

- Basic hand tools for disassembling and re-assembling the mechanical components of the electrical system should include an assortment of screwdrivers, pliers, wrenches, and a nutdriver set.

- Electrical tape should be used to protect all wire terminals from water and corrosion. By far the best is self-amalgamating tape which forms a tough, impervious layer of rubber over terminal joints. Alternatives are heat-shrink tubing and the tools to apply it properly, and a liquid sealant that will form a tough shield around wire joints.

- Pack all the supplies in a waterproof plastic box or tacklebox and stow it on board. Whenever a piece is used, donít forget to replace it at the next opportunity.

- Your kit will require almost no maintenance. Replace the batteries in the multimeter occasionally so that it will work when it is needed and to prevent battery damage to the instrument. Enter this item in your maintenance log to remind yourself. Otherwise, open the box occasionally to check for spillage and wipe the tools down with a light coating of oil to protect them against corrosion.

With the parts and tools outlined above, you will be able to find and fix any electrical problem on board short of a complete system failure.